Posted: 20/07/2014 at 13:09
The leaves look healthy.
Did you take cuttings and grow them on yourself?
If not you might have a purple beech variety in amongst the green?
History & uses of Fagus sylvatica Purpurea
Copper beech is a natural variant of green beech: about 1 in every 1000 green beech seeds will turn out to have at least partially purple or brown leaves. One of the earliest records identifying beech trees with purplish leaves dates back to Germany in the late 1400's.
Copper Beech, also called Purple Beech, may be listed as Fagus sylvatica purpurea, atropurpurea oratropunicea. They are all the same tree.